Recently, lower fuel consumption and emission requirements are driving aircraft engine original equipment manufacturers (OEM's) to increase cycle temperature and pressure ratio. As a result, nacelle and bleed air temperatures are increasing. This has led to the development of various components, such as solenoid actuators, that can operate in relatively high temperature (e.g., up to 600° F.) environments.
Presently, the process of winding the coil of a high temperature solenoid actuator begins by crimping the start end of coil, which is formed of magnet wire, to a lead wire very close to one end of the bobbin assembly. One loop of the magnet wire is wound around the bobbin assembly to provide strain relief for the coil start end. To facilitate the crimp and to further improve coil start end strain relief, the end of the bobbin assembly is machined with a groove. Unfortunately, the groove reduces the effective cross sectional area of the bobbin assembly, which reduces the magnetic performance and efficiency of the solenoid actuator, and thus the electromagnetic force generated by the solenoid actuator.
In addition to the above, it is noted that the machined groove has edges, which can damage the magnet wire during the winding and assembly process. It can also be very difficult to insert the magnet wires into the groove. In particular, to protect the coil from short circuiting and to provide good dielectric strength, multiple layers of cement saturated fiber glass tape are inserted between the coil assembly and bobbin assembly. Inserting this tape into the grooves can be a very difficult, tedious, and time-consuming process.
Hence, there is a need for a high temperature solenoid actuator that exhibits improved magnetic performance and efficiency over current solenoid actuators, and that can be simply manufactured without damaging the magnet wire. The present invention addresses at least this need.